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qgsmeshvectorrenderer.cpp
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qgsmeshvectorrenderer.cpp
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/***************************************************************************
qgsmeshvectorrenderer.cpp
-------------------------
begin : May 2018
copyright : (C) 2018 by Peter Petrik
email : zilolv at gmail dot com
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include "qgsmeshvectorrenderer.h"
#include "qgsrendercontext.h"
#include "qgscoordinatetransform.h"
#include "qgsmaptopixel.h"
#include "qgsunittypes.h"
#include "qgsmeshlayerutils.h"
#include <cstdlib>
#include <ctime>
#include <algorithm>
#include <QPen>
#include <QPainter>
#include <cmath>
///@cond PRIVATE
inline double mag( double input )
{
if ( input < 0.0 )
{
return -1.0;
}
return 1.0;
}
inline bool nodataValue( double x, double y )
{
return ( std::isnan( x ) || std::isnan( y ) );
}
QgsMeshVectorRenderer::QgsMeshVectorRenderer( const QgsTriangularMesh &m,
const QVector<double> &datasetValuesX,
const QVector<double> &datasetValuesY,
const QVector<double> &datasetValuesMag,
double datasetMagMinimumValue,
double datasetMagMaximumValue,
bool dataIsOnVertices,
const QgsMeshRendererVectorSettings &settings,
QgsRenderContext &context, const QSize &size )
: mTriangularMesh( m )
, mDatasetValuesX( datasetValuesX )
, mDatasetValuesY( datasetValuesY )
, mDatasetValuesMag( datasetValuesMag )
, mMinMag( datasetMagMinimumValue )
, mMaxMag( datasetMagMaximumValue )
, mContext( context )
, mCfg( settings )
, mDataOnVertices( dataIsOnVertices )
, mOutputSize( size )
, mBufferedExtent( context.extent() )
{
// should be checked in caller
Q_ASSERT( !mDatasetValuesMag.empty() );
Q_ASSERT( !std::isnan( mMinMag ) );
Q_ASSERT( !std::isnan( mMaxMag ) );
// we need to expand out the extent so that it includes
// arrows which start or end up outside of the
// actual visible extent
double extension = context.convertToMapUnits( mMaxMag, QgsUnitTypes::RenderPixels );
mBufferedExtent.setXMinimum( mBufferedExtent.xMinimum() - extension );
mBufferedExtent.setXMaximum( mBufferedExtent.xMaximum() + extension );
mBufferedExtent.setYMinimum( mBufferedExtent.yMinimum() - extension );
mBufferedExtent.setYMaximum( mBufferedExtent.yMaximum() + extension );
}
QgsMeshVectorRenderer::~QgsMeshVectorRenderer() = default;
void QgsMeshVectorRenderer::draw()
{
// Set up the render configuration options
QPainter *painter = mContext.painter();
painter->save();
if ( mContext.flags() & QgsRenderContext::Antialiasing )
painter->setRenderHint( QPainter::Antialiasing, true );
QPen pen = painter->pen();
pen.setCapStyle( Qt::FlatCap );
pen.setJoinStyle( Qt::MiterJoin );
double penWidth = mContext.convertToPainterUnits( mCfg.lineWidth(),
QgsUnitTypes::RenderUnit::RenderMillimeters );
pen.setWidthF( penWidth );
pen.setColor( mCfg.color() );
painter->setPen( pen );
const QList<int> trianglesInExtent = mTriangularMesh.faceIndexesForRectangle( mBufferedExtent );
if ( mCfg.isOnUserDefinedGrid() )
drawVectorDataOnGrid( trianglesInExtent );
else if ( mDataOnVertices )
drawVectorDataOnVertices( trianglesInExtent );
else
drawVectorDataOnFaces( trianglesInExtent );
painter->restore();
}
bool QgsMeshVectorRenderer::calcVectorLineEnd(
QgsPointXY &lineEnd,
double &vectorLength,
double &cosAlpha,
double &sinAlpha, //out
const QgsPointXY &lineStart,
double xVal,
double yVal,
double magnitude //in
)
{
// return true on error
if ( xVal == 0.0 && yVal == 0.0 )
return true;
// do not render if magnitude is outside of the filtered range (if filtering is enabled)
if ( mCfg.filterMin() >= 0 && magnitude < mCfg.filterMin() )
return true;
if ( mCfg.filterMax() >= 0 && magnitude > mCfg.filterMax() )
return true;
// Determine the angle of the vector, counter-clockwise, from east
// (and associated trigs)
double vectorAngle = -1.0 * atan( ( -1.0 * yVal ) / xVal );
cosAlpha = cos( vectorAngle ) * mag( xVal );
sinAlpha = sin( vectorAngle ) * mag( xVal );
// Now determine the X and Y distances of the end of the line from the start
double xDist = 0.0;
double yDist = 0.0;
switch ( mCfg.shaftLengthMethod() )
{
case QgsMeshRendererVectorSettings::ArrowScalingMethod::MinMax:
{
double minShaftLength = mContext.convertToPainterUnits( mCfg.minShaftLength(),
QgsUnitTypes::RenderUnit::RenderMillimeters );
double maxShaftLength = mContext.convertToPainterUnits( mCfg.maxShaftLength(),
QgsUnitTypes::RenderUnit::RenderMillimeters );
double minVal = mMinMag;
double maxVal = mMaxMag;
double k = ( magnitude - minVal ) / ( maxVal - minVal );
double L = minShaftLength + k * ( maxShaftLength - minShaftLength );
xDist = cosAlpha * L;
yDist = sinAlpha * L;
break;
}
case QgsMeshRendererVectorSettings::ArrowScalingMethod::Scaled:
{
double scaleFactor = mCfg.scaleFactor();
xDist = scaleFactor * xVal;
yDist = scaleFactor * yVal;
break;
}
case QgsMeshRendererVectorSettings::ArrowScalingMethod::Fixed:
{
// We must be using a fixed length
double fixedShaftLength = mContext.convertToPainterUnits( mCfg.fixedShaftLength(),
QgsUnitTypes::RenderUnit::RenderMillimeters );
xDist = cosAlpha * fixedShaftLength;
yDist = sinAlpha * fixedShaftLength;
break;
}
}
// Flip the Y axis (pixel vs real-world axis)
yDist *= -1.0;
if ( std::abs( xDist ) < 1 && std::abs( yDist ) < 1 )
return true;
// Determine the line coords
lineEnd = QgsPointXY( lineStart.x() + xDist,
lineStart.y() + yDist );
vectorLength = sqrt( xDist * xDist + yDist * yDist );
// Check to see if both of the coords are outside the QImage area, if so, skip the whole vector
if ( ( lineStart.x() < 0 || lineStart.x() > mOutputSize.width() ||
lineStart.y() < 0 || lineStart.y() > mOutputSize.height() ) &&
( lineEnd.x() < 0 || lineEnd.x() > mOutputSize.width() ||
lineEnd.y() < 0 || lineEnd.y() > mOutputSize.height() ) )
return true;
return false; //success
}
void QgsMeshVectorRenderer::drawVectorDataOnVertices( const QList<int> &trianglesInExtent )
{
const QVector<QgsMeshVertex> &vertices = mTriangularMesh.vertices();
const QVector<QgsMeshFace> &triangles = mTriangularMesh.triangles();
QSet<int> drawnVertices;
// currently expecting that triangulation does not add any new extra vertices on the way
Q_ASSERT( mDatasetValuesMag.count() == vertices.count() );
for ( int triangleIndex : trianglesInExtent )
{
if ( mContext.renderingStopped() )
break;
const QgsMeshFace triangle = triangles[triangleIndex];
for ( int i : triangle )
{
if ( drawnVertices.contains( i ) )
continue;
drawnVertices.insert( i );
const QgsMeshVertex &vertex = vertices.at( i );
if ( !mBufferedExtent.contains( vertex ) )
continue;
double xVal = mDatasetValuesX[i];
double yVal = mDatasetValuesY[i];
if ( nodataValue( xVal, yVal ) )
continue;
double V = mDatasetValuesMag[i]; // pre-calculated magnitude
QgsPointXY lineStart = mContext.mapToPixel().transform( vertex.x(), vertex.y() );
drawVectorArrow( lineStart, xVal, yVal, V );
}
}
}
void QgsMeshVectorRenderer::drawVectorDataOnFaces( const QList<int> &trianglesInExtent )
{
const QVector<QgsMeshVertex> ¢roids = mTriangularMesh.centroids();
const QList<int> nativeFacesInExtent = QgsMeshUtils::nativeFacesFromTriangles( trianglesInExtent,
mTriangularMesh.trianglesToNativeFaces() );
for ( int i : nativeFacesInExtent )
{
if ( mContext.renderingStopped() )
break;
QgsPointXY center = centroids.at( i );
if ( !mBufferedExtent.contains( center ) )
continue;
double xVal = mDatasetValuesX[i];
double yVal = mDatasetValuesY[i];
if ( nodataValue( xVal, yVal ) )
continue;
double V = mDatasetValuesMag[i]; // pre-calculated magnitude
QgsPointXY lineStart = mContext.mapToPixel().transform( center.x(), center.y() );
drawVectorArrow( lineStart, xVal, yVal, V );
}
}
void QgsMeshVectorRenderer::drawVectorDataOnGrid( const QList<int> &trianglesInExtent )
{
int cellx = mCfg.userGridCellWidth();
int celly = mCfg.userGridCellHeight();
const QVector<QgsMeshFace> &triangles = mTriangularMesh.triangles();
const QVector<QgsMeshVertex> &vertices = mTriangularMesh.vertices();
for ( const int i : trianglesInExtent )
{
if ( mContext.renderingStopped() )
break;
const QgsMeshFace &face = triangles[i];
const int v1 = face[0], v2 = face[1], v3 = face[2];
const QgsPoint p1 = vertices[v1], p2 = vertices[v2], p3 = vertices[v3];
const int nativeFaceIndex = mTriangularMesh.trianglesToNativeFaces()[i];
// Get the BBox of the element in pixels
QgsRectangle bbox = QgsMeshLayerUtils::triangleBoundingBox( p1, p2, p3 );
int left, right, top, bottom;
QgsMeshLayerUtils::boundingBoxToScreenRectangle( mContext.mapToPixel(), mOutputSize, bbox, left, right, top, bottom );
// Align rect to the grid (e.g. interval <13, 36> with grid cell 10 will be trimmed to <20,30>
if ( left % cellx != 0 )
left += cellx - ( left % cellx );
if ( right % cellx != 0 )
right -= ( right % cellx );
if ( top % celly != 0 )
top += celly - ( top % celly );
if ( bottom % celly != 0 )
bottom -= ( bottom % celly );
for ( int y = top; y <= bottom; y += celly )
{
for ( int x = left; x <= right; x += cellx )
{
QgsMeshDatasetValue val;
const QgsPointXY p = mContext.mapToPixel().toMapCoordinates( x, y );
if ( mDataOnVertices )
{
val.setX(
QgsMeshLayerUtils::interpolateFromVerticesData(
p1, p2, p3,
mDatasetValuesX[v1],
mDatasetValuesX[v2],
mDatasetValuesX[v3],
p )
);
val.setY(
QgsMeshLayerUtils::interpolateFromVerticesData(
p1, p2, p3,
mDatasetValuesY[v1],
mDatasetValuesY[v2],
mDatasetValuesY[v3],
p )
);
}
else
{
val.setX(
QgsMeshLayerUtils::interpolateFromFacesData(
p1, p2, p3,
mDatasetValuesX[nativeFaceIndex],
p
)
);
val.setY(
QgsMeshLayerUtils::interpolateFromFacesData(
p1, p2, p3,
mDatasetValuesY[nativeFaceIndex],
p
)
);
}
if ( nodataValue( val.x(), val.y() ) )
continue;
QgsPointXY lineStart( x, y );
drawVectorArrow( lineStart, val.x(), val.y(), val.scalar() );
}
}
}
}
void QgsMeshVectorRenderer::drawVectorArrow( const QgsPointXY &lineStart, double xVal, double yVal, double magnitude )
{
QgsPointXY lineEnd;
double vectorLength;
double cosAlpha, sinAlpha;
if ( calcVectorLineEnd( lineEnd, vectorLength, cosAlpha, sinAlpha,
lineStart, xVal, yVal, magnitude ) )
return;
// Make a set of vector head coordinates that we will place at the end of each vector,
// scale, translate and rotate.
QgsPointXY vectorHeadPoints[3];
QVector<QPointF> finalVectorHeadPoints( 3 );
double vectorHeadWidthRatio = mCfg.arrowHeadWidthRatio();
double vectorHeadLengthRatio = mCfg.arrowHeadLengthRatio();
// First head point: top of ->
vectorHeadPoints[0].setX( -1.0 * vectorHeadLengthRatio );
vectorHeadPoints[0].setY( vectorHeadWidthRatio * 0.5 );
// Second head point: right of ->
vectorHeadPoints[1].setX( 0.0 );
vectorHeadPoints[1].setY( 0.0 );
// Third head point: bottom of ->
vectorHeadPoints[2].setX( -1.0 * vectorHeadLengthRatio );
vectorHeadPoints[2].setY( -1.0 * vectorHeadWidthRatio * 0.5 );
// Determine the arrow head coords
for ( int j = 0; j < 3; j++ )
{
finalVectorHeadPoints[j].setX( lineEnd.x()
+ ( vectorHeadPoints[j].x() * cosAlpha * vectorLength )
- ( vectorHeadPoints[j].y() * sinAlpha * vectorLength )
);
finalVectorHeadPoints[j].setY( lineEnd.y()
- ( vectorHeadPoints[j].x() * sinAlpha * vectorLength )
- ( vectorHeadPoints[j].y() * cosAlpha * vectorLength )
);
}
// Now actually draw the vector
mContext.painter()->drawLine( lineStart.toQPointF(), lineEnd.toQPointF() );
mContext.painter()->drawPolygon( finalVectorHeadPoints );
}
///@endcond